极区夏季中间层潮汐和平均风的短期变化特征

利用德国ＳＯＵＳＹ ＶＨＦ雷达在中间层高度上６天的观测数据,研究了夏季极区中间层大气潮汐和水平风的变化特征。动态谱分析表明,半日潮是极区夏季中间层高度上占支配地位的波动;周日潮通常较弱,偶尔也会增长到与半日潮相当的强度;１／８ｃｐｈ频率附近偶尔出现较强的谱峰,但持续时间更短。潮汐谱峰对应的频率一般与其定义值有偏离,说明它们经常处在被扰动的状态。在相差２．７ｋｍ的两个高度上纬向和经向平均风的时间变化     

A physically-based model to correct atmospheric and illuminationeffects in optical satellite data of rugged terrain

A physically-based model to correct atmospheric and topographically induced illumination effects in optical satellite data is developed and tested. Special emphasis is put on the impact of rugged terrain. Ground reference data for various land use classes enables the assessment of the corrections' influence on land use classifications. The estimation of surface reflectance is achieved in a two-step procedure. First irradiance components and atmospheric parameters are calculated for horizontal surfaces using the atmo-code 6S, E. Vermonte et al. (1994), then the influence of the topography on the parameters is integrated using DEM data     

基于风电不确定出力的风电并网机组组合优化

风电出力的不确定性给风电并网调度带来一定的挑战。基于日前24小时风电预测出力与6小时准实时出力,建立风电成本模型,提出了一种新的考虑风电并网的机组组合制定方法,该方法通过6小时准实时出力与日前24小时预测出力情况来及时调整6小时内机组组合计划。在10机系统上采用所提出的方法,仿真结果表明,该方法能够根据风电出力特性合理制定机组组合,从而降低系统预留旋转备用,有效降低因风电出力不确定性所引起的发电成本。     

直接测风激光雷达频率跟踪技术及对流层平流层大气风场观测

为了实现高精度连续探测对流层和平流层大气风场,搭建了一台直接测风激光雷达系统对对流层和平流层大气风场进行探测。该系统基于双边缘法布里-珀罗标准具的瑞利散射多普勒测风原理,使用转台式探测结构,通过频率跟踪的手段对频率漂移进行跟踪,确保测风的精度。实验结果表明,该系统对对流层和平流层大气风场探测效果良好,频率跟踪的范围为±50 MHz,可以大大减小频率漂移带来的风速误差。经过系统的稳定运行和长时间的观测,在40 km处测得的径向风速随机误差为8 m/s。径向风速合成为水平风速后,随机误差在38 km处最大为10 m/s左右。该系统白天探测高度为25 km,夜晚探测高度为38 km。与探空数据对比,风速误差均小于10 m/s,其中风速误差在±5 m/s的范围内的数据量约占75.8%,探测的风向误差与探空气球的趋势基本一致,误差范围在10°～20°之间,在15°范围内的数据量约占58.6%。将实测数据与探空数据进行统计分析,结果具有良好的一致性。该系统可以为对流层和平流层大气风场的探测提供数据支撑。     

STS-768 multiplexer with full-rate output data retimer in InP HBT

A 16:1 STS-768 multiplexer IC has been designed and fabricated using the Vitesse Semiconductor VIP-1 process. This IC is part of a complete chip-set solution for a 40-Gb/s STS-768 optical communication transceiver module. The multiplexer IC features a full-rate clock multiplication unit and a data retimer in the output stage to reduce duty-cycle distortion and jitter in the output data eye. Because of its strict timing requirements, this approach needs fast logic gates with a very low gate delay. The Vitesse VIP-1 process, with 150-GHz f/sub t/ and 150-GHz f/sub max/ heterojunction bipolar transistor, is an obvious choice to implement this IC. The multiplexer IC typically dissipates 3.6 W from -3.6-V and -5.2-V power supplies. This paper discusses the design and development of a 40-Gb/s 16:1 multiplexer IC including current-mode logic gate circuit design, divide-by-two, 40-GHz clock tree, voltage-controlled oscillator, clock multiplication unit, and output driver. Layout design and package design are also discussed due to their significant roles in the IC performance.     

模型分析及测试方法计算大气调制传递函数

采用基于点扩散函数的模型分析和基于测试方法的MODTRAN计算两种方法,计算了大气调制传递函数。通过引入大气分层对调制传递函数的影响,给出一种大气折射率结构常数的综合计算方法,修正了大气调制传递函数模型,明确给出了模型中的参数及计算方法。利用MODTRAN软件计算大气调制传递函数的模型并给出了计算方法。以机载成像仪的工作环境为背景对模型进行了仿真分析,讨论了影响调制传递函数的因素,为评价大气对成像仪的影响提供了依据。     

利用WRF模式对大气波导的数值模拟研究

利用WRF模式,以NCEP再分析资料作为背景场,并同化地面自动气象站观测资料,对发生在黄淮江淮流域的一次大气波导过程进行了数值模拟与对比分析,发现WRF中尺度数值模式可以反映出大气边界层内的逆温和湿度锐减并较好的模拟大气波导的变化,同化自动站资料比不同化模拟出的波导范围扩大、波导强度增强,与雷达回波的一致性更好。     

基于多普勒激光雷达的风场预测

采用灰色理论、BP神经网络、布朗三次指数平滑算法来对雷达风场预测进行研究。利用香港国际机场激光雷达数据对风场PPI扫描风速进行预测,得到了预测时刻机场区域整个风场的概况,让飞行员能提前了解机场区域内未来一段时间的风场环境;使用下滑道扫描数据对飞机在下滑道附近的迎头风进行预测,从而更精确地预测飞机在起飞和降落过程中将会遇到的风场波动,使飞行员能够在风切变探测系统告警之前,增加飞行员进行反应和相关准备的时间。对实验结果的统计分析表明:布朗三次指数平滑预测在延长预测时间时,预测精度随时间的增加而下降的趋势较明显;灰色预测和BP网络预测在风场变化很大的情况和延长预测时间时,仍能在一定程度上保证预测精度;灰色预测较BP网络预测效果稍好。     

一种带有ARINC429输出功能的直流电压比率表设计

航空维修企业使用的直流电压比率表非常昂贵并且用途专一,采用低成本的MSP430F1611单片机为控制器设计了量程自动转换的数字电压表,可以自动测量200V以内直流电压。在此基础上实现了直流电压比率的测量和显示。采用HS3282和HS3182芯片,将直流电压比率信号转换成串行的ARINC429数据格式。数字电压比率和ARINC429数据输出测试表明,电压比率表转换精度相对较高,ARINC429数据稳定可靠,可以在航空维修、自动测试中广泛使用。     

On-panel output buffer with offset compensation technique for data driver in LTPS technology

To overcome the offset voltage (V/sub OS/) of output buffer due to large variation on characteristics of thin-film transistor (TFT) in low-temperature polysilicon (LTPS) technology, a class-B output buffer with offset compensation circuit for the data driver is presented in this paper. This proposed class-B output buffer can operate at 50-kHz operation frequency with a 2-8-V output swing for extended graphic array (XGA) application, and it has been demonstrated in 3-/spl mu/m LTPS technology. Using the offset compensation technique, the V/sub OS/ of output buffer can be controlled within /spl plusmn/100 mV under 2-to-8 V signal operation to achieve a high resolution and quality liquid crystal display (LCD) panel.     

System parameter estimation with input/output noisy data andmissing measurements

An investigation is undertaken to examine the parameter estimation problem of linear systems when some of the measurements are unavailable (i.e., missing data) and the probability of occurrence of missing data is unknown a priori. The system input and output data are also assumed to be corrupted by measurement noise, and the knowledge of the noise distribution is unknown. Under the unknown noise distribution and missing measurements, a consistent parameter estimation algorithm [which is based on an l_p norm iterative estimation algorithm-iteratively reweighted least squares (IRLS)] is proposed to estimate the system parameters. We show that if the probability of missing measurement is less than one half, the parameter estimates via the proposed estimation algorithm will converge to the true parameters as the number of data tends to infinity. Finally, several simulation results are presented to illustrate the performance of the proposed l _p norm iterative estimation algorithm. Simulation results indicate that under input/output missing data and noise environment, the proposed parameter estimation algorithm is an efficient approach toward the system parameter estimation problem     

Remote identification of in situ atmospheric silicate and carbonatedust by passive infrared spectroscopy

The authors report the remote identification of in situ airborne silicate (Si_XO_Y) and carbonate (CO₃) dust using passive infrared spectroscopy. The silicates are identified based on the 9.7 μm emission feature, a resonance due to the fundamental asymmetric vibrational mode of the O-Si-O structure. The carbonate structure from calcite (CaCO₃) was identified based on the CO bending mode resonance at 11.4 μm. Laboratory spectra of dust collected after the event confirm the high silica and carbonate content. Minimum detectable column densities are about 10^-6 to 10^-7 g/cm^-2. These will be limited by the signal-to-noise ratio (SNR) of the detection system and the change in the refractive index across the spectral feature. The technique is useful for quick, first-order identifications of aerosol clouds when in-situ probes are unavailable or when the origin (hence probable composition) of the cloud is not known     

Simultaneous wind and rain retrieval using SeaWinds data

The SeaWinds scatterometers onboard the QuikSCAT and the Advanced Earth Observing Satellite 2 measure ocean winds on a global scale via the relationship between the normalized radar backscattering cross section of the ocean and the vector wind. The current wind retrieval method ignores scattering and attenuation of ocean rain, which alter backscatter measurements and corrupt retrieved winds. Using a simple rain backscatter and attenuation model, two methods of improving wind estimation in the presence of rain are evaluated. First, if no suitable prior knowledge of the rain rate is available, a maximum-likelihood estimation technique is used to simultaneously retrieve the wind velocity and rain rate. Second, when a suitable outside estimate of the rain rate is available, wind retrieval is performed by correcting the wind geophysical model function for the known rain via the rain backscatter model. The new retrieval techniques are evaluated via simulation and validation with data from the National Centers for Environmental Prediction and the Tropical Rainfall Measuring Mission Precipitation Radar. The simultaneous wind/rain estimation method yields most accurate winds in the "sweet spot" of SeaWinds' swath. On the outer-beam edges of the swath, simultaneous wind/rain estimation is not usable. Wind speeds from simultaneous wind/rain retrieval are nearly unbiased for all rain rates and wind speeds, while conventionally retrieved wind speeds become increasingly biased with rain rate. A synoptic example demonstrates that the new method is capable of reducing the rain-induced wind vector error while producing a consistent (yet noisy) estimate of the rain rate.     

Optimizing error masking in BIST by output data modification

The error masking in conventional built-in self-test schemes is known to be around 2^–m when the output data is compacted in an m-bit multi-input linear feedback shift register. In the recent years, several schemes have been proposed which claim to reduce the error masking in a significant way while maintaining the need for a small overhead. In this paper, a completely new scheme for reducing error masking is proposed. Unlike the previous schemes in the literature, the new scheme is circuit-dependent and uses the concept of output data modification. This concept suggests modifying the original test output sequence before compaction, in order to obtain a new sequence with a reduced error masking probability. It is shown that the output data modification scheme provides a simple trade-off between the desired error masking which could run into (2^1thousands) and the area overhead needed (which would usually be equal to a 16 or 32 bit multi-input linear feedback shift register) for this masking. Finally, a formal proof is presented which establishes that despite circuit-dependency, the proposed scheme will on the average always lead to the desired error masking.     

辐射特性测量大气传输修正研究:大气辐射传输模式和关键大气参数分析

工作于大气中的光电测量（或遥感）设备接收的目标辐射信号受大气衰减和大气背景辐射影响。大气传输修正是目标辐射特性测量的一个重要环节。介绍了目前国际上实用的大气辐射传输计算模式及影响大气传输的重要大气光学参数的探测方法。对影响红外波段大气传输的重要大气光学参数作了分析,论证了辐射测量大气传输修正系统必须测量的大气参数。     

基于北京流星雷达的MLT区域大气风场研究

探测和研究大气风场是认知中高层大气结构的最重要的手段之一,其中流星雷达是一种非常好的观测大气风场的手段。为了更好地了解中纬中间层-低热层(MLT)区域大气风场的特征,本文利用2016年北京流星雷达反演的风场数据进行研究。首先研究了大气平均风场随时间和高度的变化特征,得出1~3月北京上空MLT区域的纬向风均以西风为主,经向风南风与北风交替显著,但仍以北风为主导的结论。继而对于90 km处的大气潮汐波进行研究,通过Lomb-Scargle功率谱方法和谐波拟合得出了大气潮汐随时间的变动规律,即中纬地区大气水平风场受到的潮汐波影响以半日潮汐为主、周日潮汐次之。     

Remote probing of the optical strength of atmospheric turbulence and of wind velocity

A procedure for determining the optical strength of turbulence of the atmosphere and the wind velocity at various altitudes by measuring the spatial and temporal covariance of scintillation is developed. Emphasis is placed on the development of the formal relationships that have to be inverted to obtain the desired results. For determination of optical strength of turbulence, it is a linear integral equation that is developed. However, for determination of remote wind velocity, a nonlinear integral equation is obtained. A computer approach for solving each of the equations is suggested. The configuration and performance requirements of the measurement apparatus are discussed.     

Detecting multiple errors in RAM by Self-Adjusting output data compression

A new version of Self-Adjusting Output Data Compression is put forward as a method of multiple-error detection in RAM. The parity-check matrix of a linear code with suitably large code distance is used to compress RAM content. The matrix columns are essentially generated in real time from memory addresses. The reliability of the method is determined by the code distance of the parity-check matrix used for compression. A hardware realization of the method is proposed.     

Automatic extraction and visualization of NEC-2 output data usingMatNEC

MatNEC is a series of tools that use the popular analysis program MatLab to serve as both a pre- and post-processor for a NEC-2 computational engine. The pre-processing features of MatNEC, which include interactive structure development and the generation of an ASCII-text input file, were described in detail previously. This article details the post-processing features of MatNEC, which include automatic data extraction from a standard NEC-2 output file, and subsequent visualization via a series of MatLab control figures